As well known in the electronics industry, a flip chip is an unpackaged integrated circuit (IC) chip having bond pads on which solder bumps are formed, with its active side (the surface of the chip containing the active circuit devices and bonding pads) oriented face down toward the circuit substrate, such as a printed circuit board (PCB), to which the flip chip is attached with the solder bumps. Attachment is by registering and reflow soldering the solder bumps to a conductor pattern on a substrate. An advantage of flip chips is that they allow the direct attachment of semiconductor integrated circuits to circuit boards, eliminating the need for an interfacing package.
The usage of flip chips is increasing in the electronics industry. For some applications, vertical devices such as field effect transistors (FET) are required. As known in the art, vertical IC devices are characterized by current flow through the thickness of the device chip. In the past, chips with vertical circuit devices have required wire bonding or specialized packaging. One packaging approach is to solder the device chip to a copper slug having input/output (I/O) pads wirebonded to a leadframe on a substrate. In addition to making electrical connections, the copper slug serves as a heatsink for the device. While suitably performing the intended purpose, significant additional process and material costs are incurred with such packaging practices. Accordingly, it would be desirable if a method were available by which vertical IC devices could be mounted to a substrate without conventional packaging. It would be particularly desirable if such a method could benefit from the assembly and processing advantages available with flip chip technologies.